Light deflector, light scanning apparatus and image forming apparatus

Abstract

A light deflector includes a rotary polygon mirror and a motor to rotate the rotary polygon mirror. The rotary polygon mirror includes reflecting surfaces to reflect light emitted from a light source and a hole portion provided in a rotational axis direction. The motor includes a shaft portion in the hole portion and a support member supporting the rotary polygon mirror. The support member is fixed to, and coaxial with, the shaft portion, and includes an insertion portion in the hole portion. The rotary polygon mirror includes a protruded portion near the hole portion and protruding from at least one reflecting surface orthogonal to the rotational axis direction. The protruded portion includes a fitting portion fitted to the shaft portion or the support member and in which a portion continued from a hole portion surface is protruded toward the rotation center more than the surface forming the hole portion.

What is claimed is: 
     
       1. A light deflector comprising:
 a rotary polygon mirror including a plurality of reflecting surfaces configured to reflect light emitted from a light source and a hole portion provided at a center of rotation along a rotational axis direction of the rotary polygon mirror; and 
 a motor configured to rotate the rotary polygon mirror, 
 wherein the motor includes a shaft portion inserted into the hole portion and a support member configured to support the rotary polygon mirror in the rotational axis direction, 
 wherein the support member is fixed to the shaft portion, is coaxial with the shaft portion, and includes an insertion portion inserted into the hole portion with the shaft portion, 
 wherein the rotary polygon mirror further includes a protruded portion in a vicinity of the hole portion, 
 wherein, with respect to the rotational axis direction, the protruded portion of the rotary polygon mirror is protruded from at least one surface of the rotary polygon mirror orthogonal to the rotational axis direction, 
 wherein the protruded portion includes a fitting portion in which a portion continued from a surface forming the hole portion is protruded toward the center of the rotation more than the surface forming the hole portion, and is fitted to the shaft portion or the support member, and 
 wherein, with respect to the rotational axis direction, the fitting portion is provided in an area outside an area where the plurality of reflecting surfaces are provided. 
 
     
     
       2. The light deflector according to  claim 1 , wherein an inner diameter of the hole portion in the fitting portion is smaller than an inner diameter of the hole portion in a portion other than the fitting portion. 
     
     
       3. The light deflector according to  claim 1 , wherein a protrusion amount of the protruded portion in the rotational axis direction is smaller than a thickness of the rotary polygon mirror. 
     
     
       4. The light deflector according to  claim 1 , further comprising a board on which the motor is mounted,
 wherein the protruded portion is provided on a surface on a side of the board of two surfaces of the rotary polygon mirror orthogonal to the rotational axis direction, and 
 wherein the fitting portion is fitted to the insertion portion of the support member. 
 
     
     
       5. The light deflector according to  claim 4 ,
 wherein the support member includes a support portion configured to support the surface on the side of the board of the two surfaces of the rotary polygon mirror orthogonal to the rotational axis direction, and 
 wherein a space is formed between the protruded portion and the support member. 
 
     
     
       6. The light deflector according to  claim 5 , wherein the insertion portion of the support member is protruded from an opposed surface. 
     
     
       7. The light deflector according to  claim 1 , further comprising a board on which the motor is mounted,
 wherein the protruded portion is provided on an opposed surface to the board that opposes two surfaces of the rotary polygon mirror orthogonal to the rotational axis direction, and 
 wherein the fitting portion is fitted to the insertion portion of the support member. 
 
     
     
       8. The light deflector according to  claim 1 , further comprising a board on which the motor is mounted,
 wherein the protruded portion is provided on an opposed surface to the board that opposes two surfaces of the rotary polygon mirror orthogonal to the rotational axis direction, and 
 wherein the fitting portion is fitted to the shaft portion. 
 
     
     
       9. The light deflector according to  claim 8 , wherein the insertion portion of the support member is provided on a side of the board from the fitting portion in the rotational axis direction. 
     
     
       10. The light deflector according to  claim 1 , wherein the rotary polygon mirror is formed of resin, and the support member is formed of metal. 
     
     
       11. A light scanning apparatus comparing:
 a light source; and 
 a light deflector, wherein the light deflector includes: 
 a rotary polygon mirror including a plurality of reflecting surfaces configured to reflect light emitted from the light source and a hole portion provided at a center of rotation along a rotational axis direction of the rotary polygon mirror, and 
 a motor configured to rotate the rotary polygon mirror, 
 wherein the motor includes a shaft portion inserted into the hole portion and a support member configured to support the rotary polygon mirror in the rotational axis direction, 
 wherein the support member is fixed to the shaft portion, is coaxial with the shaft portion, and includes an insertion portion inserted into the hole portion with the shaft portion, 
 wherein the rotary polygon mirror further includes a protruded portion in a vicinity of the hole portion, 
 wherein, with respect to the rotational axis direction, the protruded portion of the rotary polygon mirror is protruded from at least one surface of the rotary polygon mirror orthogonal to the rotational axis direction, 
 wherein the protruded portion includes a fitting portion in which a portion continued from a surface forming the hole portion is protruded toward the center of the rotation more than the surface forming the hole portion, and is fitted to the shaft portion or the support member, and 
 wherein, with respect to the rotational axis direction, the fitting portion is provided in an area outside an area where the plurality of reflecting surfaces are provided. 
 
     
     
       12. An image forming apparatus comprising:
 an image bearing member; 
 a light scanning apparatus configured to form an electrostatic latent image on the image bearing member, 
 wherein the light scanning apparatus includes a light source, and a light deflector, 
 wherein the light deflector includes: 
 a rotary polygon mirror including a plurality of reflecting surfaces configured to reflect light emitted from the light source and a hole portion provided at a center of rotation along a rotational axis direction of the rotary polygon mirror, and 
 a motor configured to rotate the rotary polygon mirror, 
 wherein the motor includes a shaft portion inserted into the hole portion and a support member configured to support the rotary polygon mirror in the rotational axis direction, 
 wherein the support member is fixed to the shaft portion, is coaxial with the shaft portion, and includes an insertion portion inserted into the hole portion with the shaft portion, 
 wherein the rotary polygon mirror further includes a protruded portion in a vicinity of the hole portion, 
 wherein, with respect to the rotational axis direction, the protruded portion of the rotary polygon mirror is protruded from at least one surface of the rotary polygon mirror orthogonal to the rotational axis direction, 
 wherein the protruded portion includes a fitting portion in which a portion continued from a surface forming the hole portion is protruded toward the center of the rotation more than the surface forming the hole portion, and is fitted to the shaft portion or the support member, and 
 wherein, with respect to the rotational axis direction, the fitting portion is provided in an area outside an area where the plurality of reflecting surfaces are provided; 
 a developing unit configured to develop the electrostatic latent image formed by the light scanning apparatus with toner to form a toner image; 
 a transfer unit configured to transfer the toner image formed by the developing unit to a sheet; and 
 a fixing unit configured to fix an unfixed toner image transferred by the transfer unit. 
 
     
     
       13. A rotary polygon mirror for reflecting light, the rotary polygon mirror comprising:
 a plurality of reflecting surfaces configured to reflect light emitted from a light source and a hole portion provided at a center of rotation along a rotational axis direction of the rotary polygon mirror; and 
 a protruded portion in a vicinity of the hole portion, 
 wherein, with respect to the rotational axis direction, the protruded portion of the rotary polygon mirror is protruded from at least one surface of the rotary polygon mirror orthogonal to the rotational axis direction, 
 wherein the protruded portion includes a fitting portion in which a portion continued from a surface forming the hole portion is protruded toward the center of the rotation more than the surface forming the hole portion, and is fitted to a shaft portion of a motor driving the rotational polygon mirror or a support member supporting the rotational polygon mirror, and 
 wherein, with respect to the rotational axis direction, the fitting portion is provided in an area outside an area where the plurality of reflecting surfaces are provided. 
 
     
     
       14. The rotary polygon mirror according to  claim 13 , wherein an inner diameter of the hole portion in the fitting portion is smaller than an inner diameter of the hole portion in a portion other than the fitting portion. 
     
     
       15. The rotary polygon mirror according to  claim 13 , wherein a protrusion amount of the protruded portion in the rotational axis direction is smaller than a thickness of the rotary polygon mirror.